1. Field of the Invention
The present invention relates to integrated circuit and lead frame assemblies and more particularly, to such assemblies which are implemented in a tape automated bonding (TAB) process.
2. Description of the Related Art
Tape automated bonding (TAB) is a technique for connecting conductive leads to the electrical contacts on an integrated circuit chip, known as a die. When such leads are so connected, they can be used to interconnect the integrated circuit with additional circuitry. Typically a strip of film is divided into a plurality of adjacent rectangular segments, each of which has a plurality of conductive leads etched thereon. The leads in each segment are referred to as a lead frame. A die mounted on a central portion of each lead frame is electrically connected to the inner ends of the leads in the frame in a known manner. When so assembled, the film or tape upon which the die are mounted may be wound onto reels prior to additional processing, testing and the like. After final testing, the tape is cut into individual TAB segments, each of which contains a die and an associated lead frame.
Typically the leads are arranged so that the inner extremities thereof define a predetermined rectangular pattern which corresponds to a substantially identical pattern of contacts or bumps on the integrated circuit die to which each of the leads is connected. The outer extremity of each lead may thus be used to connect the integrated circuit to other components. TAB bonding is limited in the number of leads which can be routed to an integrated circuit (IC) due to processes in fabricating the TAB tape which limit the spacing of the leads. This is a particular problem on some integrated circuits which can require as many as 250 or more leads. It would be desirable to increase the number of lead connections which can be made to an integrated circuit.